1. Field of the Invention
The present invention relates to magnetic recording and more particularly to position indicating structures on the disk.
2. Description of the Prior Art
Bothun, "Three-Film Laminate Substrate for Magnetic Disk" IBM Technical Disclosure Bulletin Vol. 18, No. 9 p 3027 (Feb. 1976) shows a disk with a polyethylene terephthalate (Mylar) film substrate coated with continuous aluminum foil, outer layers carrying magnetic coatings on their surfaces.
Koshino et al "Optical Method of the Head Positioning in Magnetic Disk Systems" IEEE Transactions on Magnetics MAG 16 pp631-633 (September 1980) describes an optically encoded magnetic recording medium with alternate colored and noncolored circular tracks on the anode-oxidized coating on the aluminum substrate just below the magnetic recording medium.
Acosta et al "Floppy Disc Embossing for Servo Applications" IBM Technical Disclosure Bulletin Vol 21, No. 10, p. 4259-4260 (March 1979) describes an embossed, spiral groove for electrostatic servo control with a magnetic-recording, floppy disk.